In the state of the art, a counting sensor, which has a Wiegand module, is known from the patent document DE 102 59 223 B3.
In this counting sensor, a permanent magnet moves relatively to the Wiegand module, which provides voltage impulses as a function of the movement frequency in corresponding time periods.
A processing electronic circuit detects the voltage impulse, and determines on the basis of the output signal of an additional sensor element and on the basis of the polarity of the voltage impulse both the movement direction of the permanent magnet and also the position of the north pole and of the south pole of the permanent magnet. On the basis of these informations, the processing electronic circuit determines a number of rotations of the permanent magnet and stores the corresponding value in a data storage.
The known counting sensor can be operated in an autonomous mode, in which no external energy supply is available. In the autonomous mode, the processing electronic circuit is supplied with energy, which is provided by the Wiegand module due to the output of the voltage impulses. The energy, which is supplied by the Wiegand module, is sufficient for the determination of the value of the number of rotations, and for the storage process of the value in the data storage, provided that clean voltage impulses are output.
In the framework of the development activities to the present invention, it has been recognized that during the operation of the known counting sensor due to particular courses of movement, which comprise a change of direction of the movement direction of the permanent magnet, the case may occur that the Wiegand module outputs rudimentary voltage impulses (runts due to direction), which are in fact recognized, which though do not provide sufficient energy in order to be able to perform the process of storing the value in the data storage.
In addition to that, it has also been recognized that the case may occur, that the Wiegand module outputs rudimentary voltage impulses in the case of an unchanged movement direction of the permanent magnet arrangement, which pulses are in fact again recognized, which though do not provide sufficient energy in order to be able to perform the process of storing the value. These rudimentary impulses result from the quality of the Wiegand wire (runts due to quality).
In this respect, there may result errors of the stored value and an inaccuracy of the counting sensor.
Furthermore, it is difficult to perform a correction, because the cases of rudimentary voltage impulses must be distinguished.